The present invention relates to a sheet finishing apparatus and an image forming apparatus, particularly to a sheet finishing apparatus for bundling sheets with images and stapling a sheet bundle and an image forming apparatus provided with the sheet finishing apparatus.
Conventionally, there has been a sheet finishing apparatus for aligning, bundling and stapling sheets with images ejected from an image forming apparatus such as a copying machine, a printer, a facsimile or the like (refer to Japanese Patent Publications (Kokai) No. 2000-72320 and No. 2003-267622). In such a sheet finishing apparatus, the sheets are ejected in a bundle with ends thereof aligned and stapled in uniform format. Accordingly, it is possible to eliminate manual processing such as manual aligning and manual stapling. Such a sheet finishing apparatus is provided with a stapler unit for driving a staple into the sheet bundle. In general, a stapler unit has a maximum stapling capacity such as 20 sheets or 30 sheets, and is designated with a grade and power consumption according to the capacity.
In the conventional sheet finishing apparatus, when a large number of sheets are stapled, it is necessary to increase a load of a staple for penetrating a sheet bundle, thereby causing a problem such that legs of a staple are bent or broken. Such a problem may be associated with low rigidity of a staple or a thickness of a sheet (especially, a cover sheet).
In view of the problems described above, an object of the present invention is to provide a sheet finishing apparatus capable of surely stapling a large number of sheets without deforming a staple, and an image forming apparatus provided with the sheet finishing apparatus.
Further objects and advantages of the invention will be apparent from the following description of the invention.